Wire harness thru firewall ideas ?? [Archive]

Perry Mitchell

09-26-2007, 09:16 AM

The LT5 motor I am using has 96 wires coming from it to make it run correctly, (16 nozzles, that's 32 wires alone!). I went to a Pull-A-Part wrecking yard and found a large wire conduit from the driver's door of a large car (A Mercury I believe) that the wires for the windows, speakers, door locks, etc go through. I used a hole saw and mounted it low on the firewall above the transmission. It can't be seen. Just remember to feed the wires through it as you install the motor or you will never get them into the opening.

Musclerodz

09-26-2007, 10:20 AM

AAW has a 22 pin firewall connector available. not sure if that is enough but one option. Another option would be a MIL-SPEC cannon plug.

Mike

jeff hanson

10-24-2007, 09:49 PM

I'm going with the Mil-spec connectors. 2, side by side. I think one is around 40 pin and the other is around 60 pin. They twist and lock together. Not cheap but very nice and solid connection with no worries.:thumbsup:

Steve1968LS2

10-24-2007, 09:52 PM

I took my harness out through the trans tunnel. The area right after the firewall ends.

Bowtieracing

10-24-2007, 10:02 PM

Thanks Guys, good comments again:cheers: Jeff you have raised the bar up to the sky with details:bow:

:woot:

ProdigyCustoms

10-25-2007, 01:36 AM

Problem with the AAW bulkhead is there is no 10 / 12 gauge pins. Mil spec is nice, but we do a lot of them exactly like Steve said, trans tunnel at firewall trans tunnel union

Overkill

10-25-2007, 06:36 AM

I used a MegaSquirt fuel injection controller for my Camaro. I ran the wires through the bulkhead that all the other wires run through. I bought a Painless wiring harness (before I knew about AAW, will probably try them on the current project) which had just enough open spots in the bulkhead to connect in the fuel injection wiring. Worked out good for me, but wouldn't have if the fuel injection setup would have been sequential instead of batch. Another option that I have thought about would be to get another bulkhead out of a late model car and cut the hole for it. Wouldn't need the fuse box part of it, but would be a some what clean install having it look "factory".

AllSpeedAndy

10-25-2007, 07:36 AM

I took my harness out through the trans tunnel. The area right after the firewall ends.

Thats were we try to run them through.:thumbsup:

eville

10-25-2007, 10:19 PM

I have plans to do something like the bottom center pic in this link.
http://www.wiresandpliers.com/harnesses.html

ohcbird

10-25-2007, 11:26 PM

Expect a nice shock if you step up to true AMP, Cannon, Siemens, Deutsch, Beru or Souraiu plugs. I'm using a Deutsch bulkhead fitting that is designed for vehicle power systems (the heavy-load pins Frank was talking about). Real easy to build- no special tools required (just patience).

When I did the engine swap in my 93 4 Runner, I used a factory harness from a later Tundra- easy day. Looks like it came with it. It's insulated / isolated from hell & 'double' waterproof.

Rybar

10-26-2007, 02:04 PM

I drilled a 2" hole in the firewall to be able to fit the factory PCM connectors through. Then used a large grommet found at a wrecker. Here's a pic (this was done after the motor was installed, hence the higher location)

http://i34.photobucket.com/albums/d125/Rybar/Picture066.jpg

rich-allen

10-30-2007, 12:18 PM

I have plans to do something like the bottom center pic in this link.
http://www.wiresandpliers.com/harnesses.html

Steve, that's a Cannon Mil-Spec plug. I don't think you can buy those plugs through wires and pliers any longer, the owner Mike Brown was killed earlier this year in a car accident. I have a couple of connections for getting those plugs if you need.

let me know,

Rich

bigtyme1

12-01-2007, 07:05 PM

where is everybody putting ther PCM?

XcYZ

12-02-2007, 06:47 AM

I'm mounting my ECM above the tunnel. I made a plate/bracket with studs and welded it in the car before it went to paint.

bigtyme1

12-02-2007, 07:09 AM

I'm mounting my ECM above the tunnel. I made a plate/bracket with studs and welded it in the car before it went to paint.
Scott, I'm assumeing you mean under the dash above the tunner. That's wah I was thinking about last night. Are you using the factory ECM? If you have any picks that would be great.

XcYZ

12-02-2007, 07:24 AM

Yep, inside the car. It's a combination bracket that I made that mounts the ECM and the Vintage Air Compaq heater core that's welded right to the backside of the firewall. I added a couple of extra studs that I can use for good grounds for other stuff under the dash. It always seems finding good, solid grounds under the dash can be a pain.

I didn't take any pics of it though.

Bowtieracing

12-02-2007, 07:25 AM

Scott, I'm assumeing you mean under the dash above the tunner. That's wah I was thinking about last night. Are you using the factory ECM? If you have any picks that would be great.

Yes i would like to see allso :yes:

HWYSTR455

12-12-2007, 07:48 AM

The 10/12GA wires are for ECU power, correct? Those don't need to run through the firewall with all the others. I have two posts that are under the dash on the driver's side, one that's full-time/batt power, the other is key-on that's triggered through a relay.

One thing to keep in mind is that there are several wires that need to be signal & noise isolated, and the connector needs to be shielded. Using a low-quality connector will produce troubles that are hard to track down. Believe me.

You can split the injector harness from the sensor harness as suggested by using two connectors, which would allow further distance from other wires to provide more isolation.

I'm always interested in ANY source for these bulkhead connectors, so all can post, I'll keep it handy.

The problem with using the harnesses as delivered from most 'kit' EFi people is that the hole needs to be massive to pass the connectors through. You can pull some of the connectors' pins out and pass just the wire, then put it back together, but that can lead to boogered pins, and difficulties pulling it back through. Me, I refuse to cut a hole that big in a classic musclecar. Against my grain!

Garage Dog 65

12-12-2007, 08:51 AM

As an aircraft avionics guy and a broadcast engineer - I'd echo the 2 connector solution. I am working on this question from another thread in this forum - so maybe we should solve this for everyone and post the results here - or in the How To section? (I haven't gotten that far in my project - so I had not started the research - but I was going down the same path)

Recommended Scenario: 2 connector solution with Mil Spec bulk head connectors and shielded sensor wiring. Plug 1 should be all the power and servo drive connections. Plug 2 should be the sensor connections with shielded wiring.

I'd be glad to do the legwork to build a solution and post some material sources if you'd like (I'm going there anyway - glad to share). If someone can tell me the scope of what you need.

Ex:

What is the max project requirement ? GM stock ECM config - or something like a FAST, Bigstuff, etc. Do you see the need for additional capacity ? If I build this for the max need you'd have additional capability if you don't need it today. Etc.

Here's one of my current vendors on connectors:

http://www.wingselectrosales.com/connectors.html

Here's one from the other thread:

http://www.newark.com/jsp/content/printCatalog.jsp?cat=connectors&display=single&page=8

PS, RyBar - beautiful install sir !!

HWYSTR455

12-12-2007, 09:16 AM

Garage Dog 65 - I'll take you up on that! I have a complete pinout of the FAST XFi box, and have done considerable amount of background on that. I know that a number of the leads in my case will not be used, and personally, I would prefer to use the smallest connector needed. REGARDLESS, I would be happy to use one that accounts for all the leads, just out of convenience.

The best scenario would be to use a 'mixed' connector, that accounts for the correct number of leads for the correct gauge wire. THAT will take going down the schematic and counting the gauge/pin/lead thing and recording. Not particularly difficult, just needs to be done. It may not be feasible to do in one connector.

As for which ECU, let me say this. All have a basic number of required sensors and drivers, correct? Like TPS, Water, IAC, ATS, Crank trigger, Cam trigger, etc. One could account for these and create a pass-through config that would generally account for most, if not all ECUs. One's that require more, like trans or whatever, could use an additional bulkhead. Just a thought...

When I get home I'll post the pinout on the FAST. Garage Dog 65, I'll be more than willing to help in any way I can, though I'm sure some have already done what we're talking about, would be nice if they anti-up, wouldn't it?

HWYSTR455

12-13-2007, 04:31 AM

Ok, here's the main harness & injector harness schematics. There are a number of options that can be used as well, which require more leads, but this is the basic. To get a better understanding, download the CComp software from FAST and install it. It creates a directory that contains ALL the schematics, including all options. The schematics are in PDF, and as a jpg, larger that I can post here, which is why I suggest the download. Hope this helps some!

Garage Dog 65

12-13-2007, 05:14 AM

Here are the PCM pinouts for my 2002 LS1 PCM from a vette. 2 connectors with 80 slots each - but many aren't used.

I don't have a harness yet - so I left the gauge column open for later. I asterisked the items I felt should be in the bulkhead connectors. Looks like we could easily get 2 bulkhead connectors with enough capacity - even if we break them into power/servo and sensor.

Jim

HWYSTR455

12-13-2007, 05:42 AM

Excellent! Ok, I think if one or two bulkhead connectors were identified and a source for them, all could use them as they choose. Maybe three would be the way to go, since some may want to use only one total bulkhead for all the leads. I think a 48-pin for a total would work, but would have to look again to be sure.

I looked at some of the connectors yesterday, there were ones that were waterproof, and oil/fuel proof that had enough pins.

V8TV

12-19-2007, 08:23 PM

How about these weatherpack bulkheads?

http://rjminjectiontech.com/images/weatherpack_22.jpg

http://rjminjectiontech.com/?p=12

bigtyme1

12-19-2007, 09:28 PM

How about these weatherpack bulkheads?

http://rjminjectiontech.com/images/weatherpack_22.jpg

http://rjminjectiontech.com/?p=12

I like this one, but is enough pins?

HWYSTR455

12-20-2007, 04:19 AM

Nope, would probably have to do 3 of them, and don't think they're RF insulated within the connector....

dhutton

12-20-2007, 05:01 AM

Nope, would probably have to do 3 of them, and don't think they're RF insulated within the connector....

OK, why do you need RF shielding within the connector if all the rest of the cable in the harness is not RF shielded? I don't think this is necessary and it doesn't gain you anything.

Don

HWYSTR455

12-20-2007, 05:46 AM

dhutton

12-20-2007, 06:09 AM

Some do have shielding, and there's also a dependance on the resistance of the conductor as well. I don't recall off the top of my head which, but once I revisit this area I can post. I just kept a mental note that it was required, though it's possible I could be wrong on that. Certainly two I know of are crank & cam sensors. Guess that might be only an issue if you mount the CD box inside...

I agree that some connectors do have shielding. I just don't think it does anything since all the wires in the harness are not shielded. Any interference or RFI etc will happen in the harness regardless of what you do with the connector. I think you would need to use shielded wires in the harness before a shielded connector would have any significant impact on performance.

Don

Bow Tie 67

12-21-2007, 10:39 AM

I brought mine up just below the firewall, right side of the trans tunnel. It is more or less hidden, although I did have the harness apart and rewired to make this mod.

bigtyme1

09-10-2008, 05:23 PM

I took my harness out through the trans tunnel. The area right after the firewall ends.

Was this in the center of the tunnel? or to the left or right? What size hole?

Dukeofsho

09-21-2008, 05:48 PM

Ive ran the Ecm wires several different ways. I Don't like using bulkhead only because that's just another place where there might be a "bad connection" It just like plumbing.. the more joints you use the more chances for leaks. I have ran the harness through the area just under the blower motor and through the kick panel. The other would be through the trans tunnel. I usually modify the arch of the tunnel so there is clearance. Sometimes the connectors are too large to go through a 1" hole. In the past I have made 2 plates with 2 half circles cut out. Once the plates are together around the harness you can install a 1" grommet.

Dukeofsho

09-21-2008, 06:05 PM